JP7042046B2 - Tire simulation methods, equipment, and programs on snowy roads - Google Patents

Description

The present invention relates to a tire simulation method, an apparatus, and a program on a snowy road surface.

In recent years, tire and fluid simulations have been proposed in order to evaluate performance such as noise performance and drainage performance due to fluid (air, water, etc.) around the tire. As a simulation method, the tire model is rolled on the road surface by a computer, the physical quantity of the tire model and the physical quantity of the fluid around the tire model are calculated, and the performance such as drainage performance is evaluated using the physical quantity. Patent Document 1 is disclosed as a related technique.

In order to simulate the behavior of a fluid, it is necessary to place the Euler element in the space where the fluid can exist. However, if more Euler elements are arranged than necessary, the calculation cost increases, and conversely, if the Euler elements are insufficient, the calculation accuracy deteriorates.

Patent Document 1 discloses a method of simulating a tire traveling on a road surface covered with a water film, assuming that the fluid to be analyzed is water. In this analysis, the length of the Euler element is calculated in consideration of the acceleration of the tire, with the problem that the analysis accuracy deteriorates when the water splashed forward by the tire goes out of the Euler element.

Patent Document 2 discloses a drive simulation method in which a slip ratio is taken into consideration for a tire on snow or soil.

Japanese Patent No. 6045898 Japanese Unexamined Patent Publication No. 2014-210488

Although Patent Document 1 discloses an appropriate simulation for a road surface covered with a water film, there is room for further improvement when simulating driving or braking on a snow-covered road surface.

In Patent Document 2, Euler elements are arranged in all the regions where the tire rolls according to the speed and the slip ratio of the tire, and the calculation cost becomes enormous.

The present invention has been made focusing on such a problem, and an object of the present invention is to provide a tire simulation method, an apparatus, and a program optimized for a snowy road surface.

The present invention takes the following measures in order to achieve the above object.

That is, the method of simulating a tire on a snowy road surface of the present invention is
A step of contacting a tire model representing a tire with a plurality of elements in a stationary state with a road surface model under analysis conditions including a predetermined load and a predetermined internal pressure, and calculating the maximum contact length L of the tire model after deformation under load. When,
With the step of setting the oiler element model in a region of at least 2 L in length including a region of 0.5 L in length from the ground contact end of the tire to the front and a region of 0.5 L in length from the ground contact end of the tire to the rear. ,
Under analysis conditions including the predetermined load, the predetermined internal pressure, the slip ratio, and the predetermined rotation speed, the deformed tire model is rolled on the road surface model, and Euler responds to the movement of the rolling tire model. In the dynamic state where the element model is moved, the step of calculating the deformation calculation of the tire model and the calculation of the snow behavior in the Euler element model by the dynamic explicit method, and
including.

In this way, the maximum ground contact length L is calculated, and the Euler element model is located in the region of 0.5 L in length from the ground contact end of the tire to the front and the region of 0.5 L in length from the ground contact end of the tire to the rear. Since the tires are arranged, the minimum required area for driving or braking on a snowy road surface is covered by the Euler element model, so that the calculation cost can be reduced without deteriorating the analysis accuracy.
Moreover, since the Euler element model is also translated according to the translation speed of the tire, the calculation cost can be reduced.
Therefore, it is possible to provide a tire simulation method and device optimized for a snowy road surface.

The block diagram which shows the simulation apparatus of the tire of this invention. A perspective view showing a tire model and Euler elements. Explanatory drawing about deformation analysis by grounding in a stationary state, and grounding deformation and rolling analysis. A flowchart showing a tire simulation method.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[Tire simulation device]
The device 1 according to the present embodiment is a device that simulates the behavior of a tire on a snowy road surface. Specifically, as shown in FIG. 1, the apparatus 1 includes a storage unit 11, a ground analysis unit 12, an Euler element setting unit 13, and a dynamic analysis unit 14. The device 1 may further include a model generation unit 10. In each of these parts 11 to 14, software and hardware cooperate by executing the processing routine of FIG. 4 in which the CPU is stored in advance in an information processing device such as a personal computer equipped with a CPU, a memory, various interfaces, and the like. It will be realized.

The storage unit 11 shown in FIG. 1 stores the tire model M1 shown in FIG. The tire model M1 is data representing a tire with a plurality of elements, and is used for numerical calculation by the finite element method. A main groove extending in the tire circumferential direction and a lateral groove extending in the tire width direction to form a block together with the main groove are formed on the ground contact surface of the tire. If necessary, sipes (thin grooves) may be formed in the block. The storage unit 11 can store the Euler element model M3 required for fluid analysis.

In this embodiment, the model generation unit 10 is provided. The general tire model M1 shown in FIG. 2 may be generated or acquired from the outside and stored in the storage unit 11. In this embodiment, the model generation unit 10 is provided, but if the tire model M1 is obtained, the model generation unit 10 can be omitted.

The ground contact analysis unit 12 shown in FIG. 1 brings the tire model M1 shown in FIG. 2 into contact with the road surface model ro in a stationary state under predetermined analysis conditions (see FIG. 3), and the tire model M1 after deformation due to a load. 'The maximum ground contact length L is calculated by the static implicit method. Specifically, the tire model M1 is assembled on the rim, internal pressure is applied, and the tire model M1 is pressed against the road surface model ro. Predetermined analysis conditions include a predetermined load and a predetermined internal pressure. Since this simulation is the same as the method described in Patent Document 1, detailed description thereof will be omitted. The contact area with the road surface model of the deformed tire model M1'is specified, and the contact length along the rolling direction (front-back direction) of the tire is calculated. Since the ground contact length differs depending on the position in the tire width direction, the maximum ground contact length L is specified.

In this embodiment, the ground analysis is performed by the static implicit method, but the dynamic explicit method may be used although the calculation cost increases. Of course, the calculation cost can be reduced by using the static implicit method rather than the dynamic explicit method.

As shown in FIG. 3, the oiler element setting unit 13 shown in FIG. 1 has a region Ar1 having a length of 0.5 L and a length of 0.5 L from the ground contact end of the tire toward the front based on the ground contact analysis result calculated by the ground contact analysis unit 12. The oiler element model M3 is set in a region having a length of at least 2 L including a region Ar2 having a length of 0.5 L from the ground contact end of the tire toward the rear. The region Ar1 means a region having a length of 0.5 L from the frontmost ground contact end of the tire ground contact ends to the front because the position of the tire ground contact end differs depending on the tire width direction. The region Ar2 means a region having a length of 0.5 L from the rearmost ground contact end of the tire ground contact ends toward the rear.

The dynamic analysis unit 14 shown in FIG. 1 rolls the deformed tire model M1'on the road surface model ro under analysis conditions including a predetermined load, a predetermined internal pressure, a slip ratio, and a predetermined rotation speed, and In the dynamic state where the Euler element model M3 is moved according to the movement of the rolling tire model M1', the deformation calculation of the tire model M1'and the calculation of the snow behavior in the Euler element model M3 are calculated by the dynamic explicit method. do. Specifically, as shown in FIG. 2, the dynamic analysis unit 14 combines the deformed tire model M1'and the Euler element model M3. After that, as shown in FIG. 3, the tire model M1'is rotated so as to translate at a predetermined acceleration, and the oiler element model M3 is moved at the same acceleration as the tire model M1'moves. The deformation of the tire model M1'and the behavior of the snow in the oiler element model M3 are calculated. The tire rotation speed (acceleration) and the tire translation speed are determined by the slip ratio. When the calculation by the dynamic analysis unit 14 is completed, the physical quantities of the tire and the snow are calculated. Since this simulation is the same as the method described in Patent Document 1 except that snow (elasto-plastic model) is set instead of water, detailed description thereof will be omitted.

[Tire simulation method]
A tire simulation method using the device 1 will be described with reference to FIG.

First, in step S100, the ground contact analysis unit 12 brings the tire model M1 representing the tire with a plurality of elements into contact with the road surface model ro in a stationary state under analysis conditions including a predetermined load and a predetermined internal pressure, and the load is applied. The maximum contact length L of the deformed tire model M1'is calculated. In the present embodiment, the static implicit method is used for the calculation of the tire model M1'after deformation.

In the next step S101, the Euler element setting unit 13 includes a region Ar1 having a length of 0.5 L from the ground contact end of the tire toward the front and a region Ar2 having a length of 0.5 L from the ground contact end of the tire toward the rear. The Euler element model M3 is set in a region having a length of at least 2 L.

In the next step S102, the dynamic analysis unit 14 rolls the deformed tire model M1'on the road surface model ro under analysis conditions including a predetermined load, a predetermined internal pressure, a slip ratio, and a predetermined rotation speed. In a dynamic state in which the Euler element model M3 is moved according to the movement of the rolling tire model M1', the deformation calculation of the tire model M1'and the calculation of the snow behavior in the Euler element model M3 are performed by a dynamic explicit method. Calculated by

In order to specifically show the effect of the present invention, the following evaluations were carried out for the following examples.

(1) Analysis accuracy Indexed with Comparative Example 1 as 100. The higher the value, the better the analysis accuracy.

(2) Calculation cost The comparative example 1 was set as 100 and indexed. The lower the number, the lower the calculation cost.

Example 1
The vehicle body speed was set to 10 km / h, the length of the Euler element in the front-rear direction was set to 300 mm, and the Euler element was translated and moved according to the translational speed according to the vehicle body speed. The wheel speed was increased so that the slip ratio increased from 0% to 300%. The maximum ground contact length L is 150 mm. The Euler element is arranged in a region having a length of 0.5 L toward the front of the tire contact end and a region having a length of 0.5 L toward the rear of the tire contact end.

Example 2
The vehicle body speed was set to 30 km / h. Other than that, it is the same as that of the first embodiment.

Comparative Example 1
The vehicle body speed was set to 10 km / h. The Euler element is not moved in translation, and the length of the Euler element required according to the vehicle body speed and the slip ratio is 1300 mm. Other than that, it is the same as that of the first embodiment.

Comparative Example 2
The vehicle body speed was set to 30 km / h. The Euler element is not moved in translation, and the length of the Euler element required according to the vehicle body speed and the slip ratio is 2800 mm. Other than that, it is the same as that of the first embodiment.

Comparative Example 3
The vehicle body speed was set to 10 km / h, the length of the Euler element in the front-rear direction was set to 150 mm, and the Euler element was translated and moved according to the translational speed according to the vehicle body speed. The slip rate was set to 300%. The maximum ground contact length L is 150 mm. This is an example in which the Euler element is insufficient as compared with the first embodiment. Other than that, it is the same as that of the first embodiment.

In Table 1, the calculation costs of Comparative Examples 3 and 1 and 2 in which the Euler element is translated are significantly reduced as compared with Comparative Examples 1 and 2 in which the Euler element is not moved in translation.

Comparing Comparative Example 3 and Example 1, it can be seen that the analysis accuracy is impaired if there is no Euler element having twice the maximum contact length L.

As described above, the method of simulating a tire on a snowy road surface of the present embodiment is
Under the analysis conditions including the predetermined load and the predetermined internal pressure, the tire model M1 representing the tire by a plurality of elements is brought into contact with the road surface model ro in a stationary state, and the maximum contact length L of the tire model M1'after deformation under the load is L. Step (S100) to calculate
The oiler element model M3 is set in a region of at least 2 L including a region Ar1 having a length of 0.5 L from the ground contact end of the tire toward the front and a region Ar2 having a length of 0.5 L from the ground contact end of the tire toward the rear. Step (S101) and
Under analysis conditions including a predetermined load, a predetermined internal pressure, a slip ratio, and a predetermined rotation speed, the deformed tire model M1'is rolled on the road surface model ro and responds to the movement of the rolling tire model M1'. In the dynamic state of moving the Euler element model M3, the deformation calculation of the tire model M1'and the calculation of the snow behavior in the Euler element model M3 are calculated by the dynamic explicit method (S102).
including.

The tire simulation device 1 on a snow-covered road surface of the present embodiment is
Under the analysis conditions including a predetermined load and a predetermined internal pressure, the tire model M1 representing the tire by a plurality of elements is brought into contact with the road surface model ro in a stationary state, and the maximum contact length L of the tire model M1'after deformation under the load is L. The grounding analysis unit 12 that calculates
Euler element model M3 is set in a region of at least 2 L including a region Ar1 having a length of 0.5 L from the ground contact end of the tire toward the front and a region Ar2 having a length of 0.5 L from the ground contact end of the tire toward the rear. Euler element setting unit 13 and
Under analysis conditions including a predetermined load, a predetermined internal pressure, a slip ratio, and a predetermined rotation speed, the deformed tire model M1'is rolled on the road surface model ro and responds to the movement of the rolling tire model M1'. In the dynamic state of moving the Euler element model M3, the dynamic analysis unit 14 calculates the deformation calculation of the tire model M1'and the calculation of the snow behavior in the Euler element model M3 by the dynamic explicit method.
To prepare for.

In this way, the maximum ground contact length L is calculated, and the Euler element model M3 is located in the region Ar1 having a length of 0.5 L forward from the ground contact end of the tire and the region Ar2 having a length 0.5 L from the ground contact end of the tire to the rear. Is arranged, the minimum required area for driving or braking on a snowy road surface is covered by the Euler element model M3, so that the calculation cost can be reduced without deteriorating the analysis accuracy.
Further, since the Euler element model M3 is also translated according to the translation speed of the tire, the calculation cost can be reduced.
Therefore, it is possible to provide a tire simulation method and device optimized for a snowy road surface.

In the present embodiment, the static implicit method is used to calculate the tire model after deformation.

In this way, it is possible to reduce the calculation cost as compared with the dynamic explicit method.

The program according to this embodiment is a program that causes a computer to execute the above method.
By executing these programs, it is possible to obtain the effects of the above method.

Although the embodiments of the present invention have been described above with reference to the drawings, it should be considered that the specific configuration is not limited to these embodiments. The scope of the present invention is shown not only by the description of the above-described embodiment but also by the scope of claims, and further includes all modifications within the meaning and scope equivalent to the scope of claims.

It is possible to adopt the structure adopted in each of the above embodiments in any other embodiment. The specific configuration of each part is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention.

M1 ... Tire model M3 ... Euler element model 12 ... Ground analysis unit 13 ... Euler element setting unit 14 ... Dynamic analysis unit

Claims (5)

The way the computer does
A step of contacting a tire model representing a tire with a plurality of elements in a stationary state with a road surface model under analysis conditions including a predetermined load and a predetermined internal pressure, and calculating the maximum contact length L of the tire model after deformation under load. When,
The length of the region from the frontmost ground contact end of the tire ground contact end to the front is 0.5 L , and the length of the rearmost ground contact end to the rear region of the tire ground contact end is 0.5 L. A step to set an oiler element model in a 2L long area,
Under analysis conditions including the predetermined load, the predetermined internal pressure, the slip ratio, and the predetermined rotation speed, the deformed tire model is rolled on the road surface model, and Euler responds to the movement of the rolling tire model. In the dynamic state where the element model is moved, the step of calculating the deformation calculation of the tire model and the calculation of the snow behavior in the Euler element model by the dynamic explicit method, and
How to simulate tires on snowy roads, including. The method according to claim 1, wherein the calculation of the tire model after the deformation uses a static implicit method. Under analysis conditions including a predetermined load and a predetermined internal pressure, a tire model representing a tire with a plurality of elements is brought into contact with the road surface model in a stationary state, and the maximum contact length L of the tire model after deformation under load is calculated. Analysis department and
The length of the region from the frontmost ground contact end of the tire ground contact end to the front is 0.5 L , and the length of the rearmost ground contact end to the rear region of the tire ground contact end is 0.5 L. An oiler element setting unit that sets an oiler element model in a certain area of 2 L in length,
Under analysis conditions including the predetermined load, the predetermined internal pressure, the slip ratio, and the predetermined rotation speed, the deformed tire model is rolled on the road surface model, and Euler responds to the movement of the rolling tire model. In the dynamic state where the element model is moved, the dynamic analysis unit that calculates the deformation calculation of the tire model and the calculation of the snow behavior in the Euler element model by the dynamic explicit method,
A tire simulation device on a snowy road surface. The device according to claim 3, wherein the calculation of the tire model after the deformation uses a static implicit method. A program that causes a computer to execute the method according to claim 1 or 2.

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